I made the same point in a less snarky way in my previous comment in this thread.

It is a very deeply embedded assumption that women are primary parents. Any man who has been an equal or primary carer for their kids will tell you that.

That is something we need to fight.

Men cannot breast feed. In the first years, the mother is the primary parent, by biological instinct of the child alone. After that, both are parents and it depends if the mother or the father is the better parent. But you have to really hate your child (which many parents of course do) to try to force them to live against their biological instincts when they are infants.